FIG. 19 is a plan view showing a fluid pressure control device for a vehicle brake system of a prior art in a state where a board and a cover are removed. FIG. 20 is a cross-sectional view of the fluid pressure control device taken along a line XX-XX of FIG. 19. As shown in FIGS. 19 and 20, the fluid pressure control device for the vehicle brake system of the prior art includes a solenoid valve 2 for opening and closing a fluid channel through which brake fluid flows, a board 5 on which electronic components are arranged, a resin case 3 accommodating a solenoid 21 of the solenoid valve 2 and fixing the board 5, and the like.
The board 5 has the electronic components arranged thereon. An end of a connector terminal 6 is connected with the board 5. A plurality of mounting holes are formed at the board 5. The case 3 has a solenoid housing 32 accommodating the solenoid 21, a connector housing 33 accommodating the other end of the connector terminal 6, and a joint portion 34 through which the solenoid housing 32 is connected with the connector housing 33. A plurality of board-holding units 35 and 36 are also formed at the case 3 and inserted and fitted to the mounting holes of the board 5 so as to fix the board 5. The board-holding units 35 and 36 are respectively provided at the joint portion 34 and the solenoid housing 32. A resin cover 4 is airtightly welded to a side of the case 3 opposite to the solenoid 21. Thus, the case 3 and the cover 4 form a board housing chamber 41 in which the board 5 is installed (for example, see Japanese Unexamined Patent Application Publication No. 2002-368452).
However, since the fluid pressure control device for the vehicle brake system is generally mounted in an engine room of a vehicle, the resin case 3 may be deformed by, for example, heat generated at an engine. In particular, the connector housing 33 may noticeably warp because the connector housing 33 extends from the solenoid housing 32 in an overhanging manner.
More specifically, the case 3 may be deformed such that the connector housing 33 turns around an axis K of the joint portion 34 with respect to the solenoid housing 32. Accordingly, a solder bonding portion 8 between the connector terminal 6 and the board 5 may be displaced in an F direction.
A component in an x direction of the displacement F is restricted by the board-holding unit 35 provided at the joint portion 34. Another component in a y direction of the displacement F causes a frictional resistance between the board-holding unit 35 provided at the joint portion 34 and the board 5. As a result, stresses are generated at the solder bonding portion 8 in both the x and y directions, thereby making solder cracking more likely to occur.
In addition, a residual stress is generated in forming the case 3 and causes distortion (more specifically, warpage) of the case relative to a point close to the axis K. Therefore, it is difficult to manufacture the case 3 with high dimensional accuracy. This may harm reliability of sealing at a welded portion between the case 3 and the cover 4.